Search

We compare Ha, radio continuum, and Spitzer Space Telescope images of 58 planetary nebulae (PNe) recently discovered by the Macquarie-AAO-Strasbourg Ha PN Project (MASH) of the SuperCOSMOS Ha Survey. Using Infrared Array Camera (IRAC) data, we examine the relationships between optical and MIR morphologies from 3.6 to 8.0 mm and explore the ratio of mid-infrared (MIR) to radio nebular fluxes, which is a valuable discriminant between thermal and nonthermal emission. MASH emphasizes late evolutionary stages of PNe compared with previous catalogs, enabling study of the changes in MIR and radio flux that attend the aging process. Spatially integrated fluxes are constructed for all MASH PNe observed by the GLIMPSE Legacy Project, using the Ha morphologies to define the areas of MIR and radio continuum emission observed by the Midcourse Space Experiment (MSX), IRAC, the Molonglo Observatory Synthesis Telescope, and the Very Large Array (VLA). The ratio of IRAC 8.0 mm to MSX 8.3 mm fluxes provides an assessment of the absolute diffuse calibration of IRAC at 8.0 mm. We independently confirm the aperture correction factor to be applied to IRAC at 8.0 mm to align it with the diffuse calibration of MSX. The result is in accord with the recommendations of the Spitzer Science Center and with our results from a parallel study of H II regions in the MIR and radio. However, these PNe probe the diffuse calibration of IRAC on a spatial scale of 9''-77'', as opposed to the many-arcminute scale from the H II regions' study.

We present a new planetary nebula, first identified in images from the Australia Telescope Compact Array, although not recognized at that time. Recent observations with the Spitzer Space Telescope during the GLIMPSE Legacy program have rediscovered the object. The high-resolution radio and infrared images enable the identification of the central star or its wind, the recognition of the radio emission as thermal, and the probable presence of polycyclic aromatic hydrocarbons in and around the source. These lead to the conclusion that G313.3+00.3 is a planetary nebula. This object is of particular interest because it was discovered solely through radio and mid-infrared imaging, without any optical (or near-infrared) confirmation, and acts as a proof of concept for the discovery of many more highly extinguished planetary nebulae. G313.3+00.3 is well resolved by both the instruments with which it was identified and suffers extreme reddening due to its location in the Scutum-Crux spiral arm.